Treatment of glyceride oils



Patented Oct. 3, 1950 UNITED STATES. PATENT OFFICE TREATMENT or GLYCERIDE orLs Stewart W. Gloyer, Milwaukee, Wis., assignor to Pittsburgh Plate Glass Company, Allegheny County, Pa, a corporation of Pennsylvania Application September 7, 1945, Serial No. 615,027

6 Claims, (01. 260-4285) such as phospholipids, lecithin, gums, and the like in order to refine them and to separate out the constituents, in a manner admitting of their more satisfactory application in the arts.

The objects of the invention comprise:

Firstly, to provide a process whereby oils including mixtures of the foregoing constituents may be refined in order to free all or a portion of the glyceride components of the acids, the break constituents, inhibitols, or the like which may be objectionable therein;

Secondly, to provide a process as specified above in which the oil is also fractionated into a relatively highly unsaturated portion and a relatively highly saturated portion;

Thirdly, to obtain a concentrate of free fatty acids and unsaponifiables such as sterols, inhibitols, tocopherols and vitamins which with or without further fractionation and processing is of great value as a source of pharmaceuticals, soap constituents, resin constituents and other valuable products;

Fourthly, to provide a process of refining glyceride oils to obtain an oil product which is free of break, gum, free fatty acids, and other constituents which are objectional in the glycerides as normally employed, in which process the losses accompanying refining are reduced to a minimum.

These and other objects will be apparent from consideration of the following specification and claims.

It has heretofore been recognized that natural glyceride oils such as soya bean oil, linseed oil, cottonseed oil, menhaden oil, fish liver oils and the like include as their main constituent glyceridea of the higher fatty acids, but that they also include free fatty acids, break constituents, sterols, inhibitols, tocopherols, vitamins, and many other constituents. In most cases, since all of the constituents except the glycerides occur in relatively small amounts, they, heretofore, have either been disregarded or have been eliminated by radical chemical treatment which results in their destruction or their degradation.

It is to be recognized that the .glycerides constituting the main component of a conventional glyceride oil usually comprises a complex mixproportions of both types of glycerides.

2 ture of the glycerides of a number of fatty acids which differ among themselves primarily by reason of differences in the degree of unsaturation of the hydrocarbon nuclei of the acids. There is much variation in the ratio of unsaturated acids and the degree of unsaturation of the acids which are combined with glycerol to provide the glycerides. Oils, such as linseed oil, tung oil and the like, which are employed in the manufacture of paints and varnishes contain a very high proportion of unsaturated glycerides while most of the food and soap oils, such as coconut oil, cottonseed oil, lard and the like, contain only a small proportion of highly unsaturated glycerides so that they have little or no capacity for drying to form hard protective films. Certain other oils, such as soya bean oil and the like, are of intermediate character, containing considerable They have, heretofore, been conventionally employed in foods but they are also susceptible of use in paints and varnishes.

In prior patents, No. 2,200,390 or 2,200,391, is disclosed, among others, a process for the fractionation of various oils upon the basis of unsaturation of the glycerides whereby there is obtained a concentration of the more saturated components especially useful for food purposes in a second fraction. This effect is obtained by suitably extracting the oil with a polar solvent in appropriate ratio and at a suitable temperature in order partially to dissolve the oil in the polar solvent. The more highly unsaturated glycerides dissolve more readily in these polar solvents than do the highly saturated glycerides so that the two types of glycerides can thus be fractionated from each other.

The present invention contemplates the provision of a process of extracting glyceride oils (preferably natural unrefined unpolymerlzed glycerlde oils) comprising mixtures of glycerides of varying degrees of unsaturation, free fatty acids, sterols, tocopherols, inhibitols, break" constituents, vitamins and many other non-saponifiable ingredients in order to obtain therefrom concentrates of the various components in undamaged condition and relatively free of other components which may be objectionable therein. For example, there is obtained a first rafiinate of low solubility in furfural. This fraction will vary in amount dependent upon the oil treated and the subsequent uses contemplated for the fractions. It may be small so as to comprise a concentrate of the "break components that can b further treated economically and with little loss of oil.

The giycerides in the raflinate are of higher saturation than the original oil. Secondly, there is obtained a-dissolved extract containing a small 7 amount of break" and a concentrate of the more unsaturated glycerides, the fatty acids, and soluble unsaponifiables. The extract solution is then sent to a still where some or all the solvent is removed. The partially or completely stripped oil is then extracted in a second column with wet polar solvent generally containing from 1 to 15% water, so as to leave in the wet solvent extract solution a fraction low in glyceride content and high in free fatty acids and unsaponifiables such as sterols, tocopherols, inhibitols and the like as well as the traces of break constituents left in the extract solution from the primary extraction. A refined extract oil. consisting of the more highly unsaturated glycerides of the original feed oil, is obtained from the railinate position of the second column.

The treatment of the whole oil in order to obtain fractionation as well as a separation of the glycerides from the minor constituents and to obtain a concentrate of fatty acids and unsaponifiable constituents as above described may be effected in accordance with the provisions of the present invention by means of a two column system, in the first of which the whole oil is extracted, preferably, countercurrently with a selective polar solvent in accordance with the provisions of the prior patents above referred to. When the oil is so treated in the first column, two liquid phases are obtained, one comprising a concentrate of the more highly saturated glycerides and brea saturated with some solvent and the other comprising the solvent saturated with the more highly unsaturated glycerides and also containing dissolved therein .aconcentrate of the coloring matter, unsaponifiables" such as sterols, inhibitols, tocopherols and the like together with the free fatty acids. In accordance with this invention this latter phase is sent to a still whereby some (generally 70 to 90%) or all of the solvent is removed, and this oil or oil-polar solvent solution is then fed to a second column where it is re-extracted with polar solvent having dissolved therein about 1 to 15% water. This re-extraction is conducted in such a manner so as to obtain as a rafiinate the major portion of the glyceride oil from the extract phase of the first column and to leave in solution in the wet solvent a small amount of unsaturated glycerides (generally not more than 5% and usually 2% or less on the basis of total oil) coloring matter, free fatty acids, and unsaponifiables such as tocopherols, inhibitols, and sterols. The latter solution can then be treated by distillation or otherwise to remove the solvents to obtain a concentrate of the foregoing ingredients, the concentrate can further be treated chemically or physically in order to separate the various constituents for use in food and drug products or for other purposes to which the particular constituents of the fraction may be especially adapted.

Various organic polar solvents which may be used in the primary fractionation in column No. 1 are included in Freeman Patents Nos. 2,200,390 and2,200,391. Asolutionofthesesolventsandsufiicient water to preclude substantial absorption of fatty acid glycerides may be used in the second column for the removal of free fatty acids, traces of break material, and unsaponifiables such as sterols, tocopherols, inhibitols and coloring matter from the primary extract oil produced in 4 column No. 1. It, of course, goes without saying that the solvent should also be inert or non-reactive with respect to the oil and its constituents, or to water at the temperatures of operation. Extraction with furfural is especially meritorious.

Assuming that furfural is employed as the selective solvent in the first column of the system, furfural saturated with naphtha in a ratio of about 3 to 15 parts per part of oil is fed into the top of the first column and the crude or degummed oil usually plus 10 to 25% naphtha is fed in near the middle of the column and an extracted oil or a naphtha reflux or a combination of extracted oil and naphtha reflux is fed in near the bottom of the same column. The rafllnate solution from this column contains most of the break'' concentrated in it. This rafiinate may be stripped of residual solvent first by vacuum distillation, then by vacuum and steam stripping and may be treated to remove break, if so desired, in accordance with conventional procedures.

The extract solution from the first column is sent to a still whereby some (generally 10 to or all of the furfural is removed and this oil or oil-furfural solution is then fed to a second column where it is i e-extracted with furfural having dissolved therein about 4 to 5% water, the amount of wet solvent generally being within the range of 1 to 6 parts of wet furfural to one part of oil. This re-extraction is conducted at such a solvent ratio and temperature so as to obtain the major portion of the glyceride oil from the extract phase of the first column as a rafllnate, and to leave in solution in the wet furfural a small amount of unsaturated glycerides (generally not more than 5% and usually 2% or less on the basis of total oil), coloring matter, free fatty acids and the like. The raffinate oil coming from the top of the second column is of a light color, break free and of low acid value. The furfural remaining in the railinate solution may be removed by evaporation. The resulting product is comparable to an extract produced from an alkali refined, break free feed oil.

The by-product remaining in the furfural is a concentrate of the coloring matter, free fatty acids and unsaponifiable matter. The unsaponifiable matter includes sterols, antioxidants, inhibitols, tocopherols, natural pigments and other unidentified compounds. This by-product is a good source of raw material for the various unsaponifiable constituents by virtue of their increased concentration as compared with the original oil.

Although the above described mode of procedure is preferred, an optional method involves adding sufficient water at the desired temperature to the extract solution from column No. I, or to an extract solution after the removal of part of the solvent by distillation, so as to precipitate out the fatty acid glycerides and leave in solution in the wet solvent the free fatty acids, coloring matter, and unsaponifiable matter such as sterols, tocopherols, inhibitols and the like.

The following are some of the results accomplished: Firstly, there is obtained a concentrate of lecithin, phosphatides and other break material in the raffinate; secondly, there is obtained a break free varnish or edible oil in accordance with the nature and purpose of the original 011 without the use of conventional chemical refining; thirdly, there is a concentration of the unsaponifiable matter, free fatty acids and coloring matter in a by-product amounting generally to 0.5% to of the original 011.

An appropriate embodiment of apparatus for use in the practice of the invention'is illustrated diagrammatically in the single figure of the drawing. The apparatus included columns I and 2 formed of any appropriate material and being of a suitable length. The columns may be provided with jackets (not shown) for the circulation of suitable heat control medium in order to obtain a desired temperature in the oil being extracted. The oil (e. g. raw or degummed cottonseed oil, linseed oil, soya bean oil, etc.) admixed with to 25 percentof naphtha, if so desired, is fed into the column I near its mid portion as indicated at 'I and asolvent medium such as anhydrous furfural, ethyl acetoacetate or the like, saturated with naphtha is fed in at the top of the column as indicated at 8. The

' ratio of oil to solvent preferably is between the limits of 1 to 3 and 1 to 20. A line 9 is also provided for feeding naphtha to the lower zones of the column. This feeding is optional and may be controlled by means of a valve indicated diagrammatically at II Raflinate comprising a concentrate of the more saturated glycerides, break constituents, such as phosphatides, lecithin, and the like and some dissolved solvents from the column passes out through line I2 and may be subjected to appropriate treatment. It may be further extracted orthe solvent dissolved therein may be removed by evaporation and returned to the system. The saturated glycerides constituting the fraction are appropriate for various purposes such as food oils or as soap stock, resin manufacture, etc.

The extract fraction comprising mainly solvent such as furfural saturated with glycerides, unsaponifiables, coloring matter, and the like passes out through the line I3. The fraction, if preferred, can be stripped partially or completely of its solvent medium in a suitable still indicated diagrammatically at I4. The glycerides comprisdrawn through the conduit l6 while the solvent removed passes out through conduit I1 and may be recycled. A by-pass, line 23, is provided whereby any desired portion of the extract solution from column No. I may by-pass still No. I4 so that any desired concentration of furfural and extract oil within a working range may be fed to column No. 2.

All of the oil extract or such portion as may be desired, passing throungh the conduit I6 is discharged into the column 2 for a second extraction with furfural saturated with water admitted through conduit I8 to the top of the column in order to remove free fatty acids, and unsaponifiables such as sterols, tocopherols and inhibitols. The wet furfural containing about 5% of water is used in a ratio of about 1 to 2 parts by weight per part of oil passing through the column. 2 The system is preferably maintained at about 70 F. The wet furfural descends countercurrently through the column and is discharged through outlet I9, to a suitable stripping device such as a still 33 where the solvent may be removed. The extract from the still passes off at 34 to storage or for further treatment in order to obtain the various components present in this by-product. The solvent from the distillation may be returned from the still through line 32 for re-use or for storage as may be desired. The

in the same column.

wet furfural fraction contains most of the free fatty acids, the unsaponiflable mattersuch as sterols, tocopherols, inhibitols and some of the vitamins as well as coloring matter.

Usually it is desirable to return a portion of the primary extract oil which has concentrated in it the more unsaturated glycerides as a reflux to column No. I. The amount of extract oil returned as reflux is generally within the range of 10 to 90%. A portion of the extract oil which has been partially or completely stripped of solvent in still No. I 4 may be fed to column No. I as reflux through line 22. Conventional valves 24 in the lines I3, I6, 23 and 22 permit the control of the flow of the extract phase from column No. I in such a manner as to by-pass any desired portion of theoil about still I 4 or to enable the stripping and refluxing of anydesired portion.

Naphtha may be fed from tank 21 to the lower portion of column No. 2 through line 26 or if it is so desired naphtha from tank 21 may be proportioned into line I6 through line 5 so that it enters the column with the feed oil. The amount of naphtha fed into column 2 through line 26 or line 5 is controlled by conventional valves 6. Naphtha comprises any hydrocarbon or mixture of hydrocarbons which is immiscible with furfural or the polar solvent being used and usually comprises a mixture of heptanes, octanes, nonanes and decanes.

The refined oil comprising the more highly unsaturated glycerides passes out through line 2| at the top of column 2. This fraction may be passed in its entirety to a still 28 through lines 2| and 21 for the removal of the solvent, the refined, highly unsaturated glyceride oil passing off through line 29 to storage, and the solvent being removed through line 3I for re-use in the system. If preferred, a portion of this more highly unsaturated fraction may be returned as a reflux through an optional line 31 to the lower portion of column I. If desired, the ratio of solvent to oil in such reflux may be reduced by passing the reflux through a suitable still 38.

Furfural, all angles considered, is of outstanding merit as the solvent for use in the column I. Wet furfural is also highly meritorious for use in column 2. However, other non-reactive organic polar solvents which within a reasonable range of temperature become partially miscible with soya bean oil, linseed oil, cottonseed oil or other natural glyceride oils may be used. Many such solvents are listed in prior Patents Nos. 2,200,391 and 2,320,738.

Various combinations of solvents are permissible in the system, one involving a dry polar solvent (furfural) in column I and the same solvent wet with water in the second column. A second system would involve the use of a single wet solvent in columns I and 2. In such a system, the first column would be elevated at a temperature sufiiciently high to render the oil glycerides partially miscible in the wet solvent. An extract of 25 to percent of the oil would be a good average. The extract phase can then be passed to column 2 for cooling to separate the glycerides. This separation can be promoted by a slight naphtha wash through line 25 as previously described.

A third system would involve the use of different solvents in the columns I and 2. The column I, for example, may be operated with dry ethyl or methyl acetoacetate or with wet acetone. The solvent is then stripped off in still I4 for re-use The extract fraction is then passed to column 2 for extraction with wet furfural.

The following tables contain the operating condltions and product data for extracting and refining soya bean oil in a system such as that above described. In these runs. column I was operated with naphtha saturated furfural and column 2 was operated with furfural saturated with water and naphtha at 70 F.

Run No. 1

Boys Bean Oil Column Temperatures I. nit-118 F.; II. 70 F. Column Feeds:

Oil Feed to column 1 12% by weight naphtha.

Fur-Intel feed to column 1 8 to 1 based on oil feed rate.

Oil reflux to column 1-.- 1.1 to 1 based on oil feed rate.

Soya Bean Oil Column Temperatures I. 116-ll8 F.; II. 70 F. Column Feeds:

Oil feed to column 1 12% by weight naphtha.

Furfural feed to column 1..-. 8 to 1 based on oil leed rate.

Oil reflux to column 1 1.1 to 1 based on oil feed rate.

N aphtha reflux to col. 1..---- None.

Wet luri'ural iced to col. 2-.. 1.25 to 1 based on oil feed rate to column 2. Oil feed to column2 63.l%hoil, 20.1% furfural; 16.8%

nap a. Naphtha dilution to oil feed 0.28 to 1 based on oil feed rate to col. 2. col. 2.

Product Data Original Ratii- By-Prod- Product on Extract Date not Taken from linc.. 21 l2 19 Yield. 55. 2 43. 0 1. 8 Iodine Value.-- 135. 4 149. 9 117. 0 149. 4 Acid Value. 0. 5 0.36 0.16 34. 9

In these two runs the extract solution from column 1 was sent to an evaporator which reduced the solvent content to 17% by weight.

This solution consisting of 83% oil and 17% solvent was fed directly to column 2 in run No. 1. In the second run the above solution was diluted with naphtha before being fed into the column.

The process described may be operated primarily for refining crude or raw oil by taking out break constituents such as phosphatides and lecithin in a glyceride ramnate from column 1 and a refined extract from the top of column 2, this said extract being more insoluble in wet solvent than the free fatty acids, traces of "break" constituents and unsaponifiable matter such as sterols, inhibitols, tocopherols and the like. In such a process it is desirable to make the rafllnate of column 1 as small as possible consistent with adequate separation of the break from the furfural extract. It is also possible to so operate as to obtain a refined extract of substantially increased iodine value from the top or normal rafilnate position to so operate as to obtain a refined extract of substantially increased iodine value from the top or normal raffinate position of column 2, this said extract being more insoluble in wet solvent than the free fatty acids, traces of "break and unsaponifiable matter. In either event, a solution comprising a concentrate of the free fatty acids, inhibitols, tocopherols and sterols together with a little glyceride oil is obtained as a, by-product from column 2. This by-product, as previously stated, is eminently suitable for further treatment to obtain the free fatty acids, inhibitols, tocopherols, and sterols as partially or completely separated components. A convenient process of so treating the by-product comprises distilling the furfural, saponifying the free acids with alcoholic sodium or potassium hydroxide and then distilling of! the alcohol. The soaps can be dissolved in water and the sterols, inhibitols, tocopherols, and other unsaponifiable constituents dissolved out in petroleum naphtha or other suitable solvent. The sterols can be crystallized from the naphtha.

Other well-known methods which may be used for further concentrating and recovering the unsaponifiable matter from the by-product might include: (1) Evaporating solvent, twitchellizing the oily stock to form fatty acids, distilling the fatty acids and recovering the unsaponiflable matter from the still bottoms in the conventional manner described above, or (2) preparing esters of the fatty acids present in the by-product with monohydric alcohols such as methyl alcohol by a process of alcoholysis or any other conventional method, distilling the methyl esters and recovering the unsaponifiable matter from the still bottoms in the conventional method described above.

The forms of the invention herein disclosed are to be regarded as merely constituting examples illustrating broad principles of operation. Numerous modifications can be made therein without departing from the spirit of the invention or the scope of the claims.

I claim:

'1. A process of recovering the free fatty acids, sterols, inhibitols, tocopherols from a concentrate thereof in an extracted oil obtained by contacting soybean oil with dry furfural and evaporating off 70 to of the furfural, the steps comprising introducing 1 volume of the extracted oil dissolved in residual furfural into a lower portion of an extraction zone and introducing 1 to 6 volumes of a. water saturated solution of furfural at a temperature of about 70 F. into an upper portion of said zone, permitting the oil and the furfural to flow countercurrently through the extraction zone in order selectively to extract the free fatty acids, sterols, tocopherols and inhibitols, then separating the phases.

2. In a process of obtaining glyceride oil of high iodine value, low in free fatty acids, sterols and inhibitols from an oil containing them in admixture with glycerides of low iodine value, the steps which comprise extracting the oil in a first zone with 4 to 20 volumes of dry furfural per volume of oil in countercurrent flow to the oil and at a. temperature below that of complete miscibility of oil and furfural, separating off a furfural extract phasefrom which the glycerides of low iodine value have been separated, evaporating a part of the furfural from the extract phase, a substantial amount of furfural, but less than 70% of that initially in said phase, remainlng, extracting off a by-product from said extract phase, comprising .5 to of the oil by introducing the extract phase after partial evaporation of the furfural into a lower part of a second extraction zone while introducing furfural wet 5 with water into an upper part of the same zone allowing the wet furfural and oil to fiow in countercurrent contact in said zone and separating the phases.

3. A process as defined in claim 2 in which the 10.

iurfural extract solution at the time of its introduction into the second zone contains approximately 17% of iurfural.

4. A process as defined in claim 2 in which tn? oil extracted is soybean oil and the second extraction zone is mainta ned at a temperature of about 70 F.

5. A process as defined in claim 2 in which 10 to 90% of the extracted oil is returned as a reflux to a'lower portion of the first extraction zone. 20

6. In a process of obtaining glyceride products of relatively high iodine value and which are relativelylow in fatty acids, sterols and inhibitols, from soya bean oil containing them in admixture with glycerides of low iodine value, the steps of 5 introducing the oil into an intermediate portion of a first zone of extraction having a first extremity and a second extremity, introducing dry furfural in a proportion of 4 to 20 volumes per volume of oil near the first extremity of the zone to effect countercurrent flow of the oil and the furfural, and to form (1) a first extract solution of furfural containing 25 to 80% of the oil, the extract oil containing a relatively increased proportion of coloring matter, fatty acids, sterols,

inhibitols and glycerides of high iodine value and by-product constituting .5 to 5% of the original oil and comprising a concentration of fatty acids, coloring matter, sterols and inhibitols, and to obtain a second rafilnate of glycerides of relatively high iodine value, low in free fatty acids, low incoloring matter, sterols, and inhibitols, and evaporating off solvents from the second raflinate to obtain said product.

STEWART W. GLOYER.

REFERENCES arm!) The following references are of record in the file ofv this patent:

UNITED STATES PATENTS Number Name Date 1,659,790 Starrels Feb. 21, 1928 2,200,390 Freeman May 14, 1940 2,200,391 Freeman May 14, 1940 2,280,815 Fernholz Apr. 28, 1942 2,349,270 Hickman May 23, 1944 2,349,271 Baxter May 23, 1944 2,355,605 Ruthrufi et al Aug. 15, 1944 

1. A PROCESS OF RECOVERING THE FREE FATTY ACIDS, STEROLS, INHIBITOLS, TOCOPHEROLS FROM A CONCENTRATE THEREOF IN AN EXTRACTED OIL OBTAINED BY CONTACTING SOYBEAN OIL WITH DRY FURFURAL AND EVAPORATING OFF 70 TO 90% OF THE FURFURAL, THE STEPS COMPRISING INTRODUCTING 1 VOLUME OF THE EXTRACTED OIL DISSOLVED IN RESIDUAL FURFURAL INTO A LOWER PORTION OF AN EXTRACTION ZONE AND INTRODUCING 1 TO 6 VOLUMES OF A WATER SATURATED SOLUTION OF FURFURAL AT A TEMPERATURE OF ABOUT 70* F. INTO AN UPPER PORTION OF SAID ZONE, PERMITTING THE OIL AND THE FURFURAL TO FLOW COUNTERCURRENTLY THROUGH THE EXTRACTION ZONE IN ORDER SELECTIVELY TO EXTRACT THE FREE FATTY ACIDS, STEROLS, TOCOPHEROLS AND INHIBITOLS, THEN SEPARATING THE PHASES. 